This invention relates to the apparatus for automatic packaging of powder material, as cement, flour, grain, fertilizer, insecticide, and the like. More particularly, the invention relates to a valve bag feeding method and machine for such packaging apparatus, wherein the bags are picked up one at a time from a magazine to be placed on a filling spout of a packaging apparatus.
Normally said materials are packaged in bags of paper or other material, which are provided on a pair of end edges with two flanges as bellows, wich are folded on one face of the bag. One of the flanges is provided with a valve, which closes automatically due to the pressure of the packaged material.
In a known bag feeding machine of the above type, the bag to be fed is picked up by grippers engaging the valve flange. The grippers rock the picked bag and carry it toward the spout upon causing the flange to cross a funnel for opening the valve. This machine has a disadvantage in that, the grippers are carried by a shaft which must rotate and translate through reciprocating movements, which require long dead times and produce a rather low speed movement of the bag. Furthermore, the funnel is located close to the spout, whereby after having guided the bag, the funnel must be removed to allow the bag to be filled.
The main object of the invention is to provide a bag feeding machine, which assures the introduction of the bag on the spout, without interfering with the filling operation.